#ifndef VLIBC_FCNTL_H
#define VLIBC_FCNTL_H

/*
 * vlibc — <fcntl.h>.
 *
 * File control, record locks, and the open-flag constants (POSIX.1-2008 plus
 * the Linux x86_64 additions). Every O_*, F_*, AT_* and POSIX_FADV_* value
 * below is a Linux kernel UAPI fact for x86_64 (asm-generic/fcntl.h), transcribed in
 * hex with the kernel's octal form in a comment — not an invented number.
 * O_TMPFILE and O_SYNC are defined as flag combinations exactly as the
 * kernel defines them.
 *
 * Note on the *at constants: on x86_64 AT_EACCESS == AT_REMOVEDIR == 0x200;
 * the kernel disambiguates by syscall (faccessat vs unlinkat), so both names
 * carry the same value here.
 *
 * open/openat are deliberately NOT declared here: POSIX places them in this
 * header, but this project's single declaration site is <unistd.h> (todo 19;
 * see its header comment). creat() lives here — its canonical POSIX home.
 *
 * Level 2 (muslmimic/XSI): lockf plus F_LOCK/F_TLOCK/F_ULOCK/F_TEST. POSIX
 * puts lockf in <unistd.h>; that file is todo 19's and out of scope here,
 * and musl declares lockf in <fcntl.h> as well — the constants accompany the
 * declaration so the header stays self-contained. A later integration pass
 * may re-export the same declaration from <unistd.h> (identical, harmless).
 *
 * None of these declarations carry an intent attribute: every function
 * performs I/O with side effects and reports failures through errno (or,
 * for posix_fadvise/posix_fallocate, an error-number return), so const/pure
 * would be unsound — the same rationale unistd.h documents for its I/O
 * family.
 */

#include <vlibc/features.h>

#include <stddef.h>

#include <sys/types.h>

#ifdef __cplusplus
extern "C" {
#endif

/* ---- open(2) flag bits ---- */

/* Mask for the O_RDONLY/O_WRONLY/O_RDWR access mode. */
#define O_ACCMODE 0x3

#define O_RDONLY 0x0 /* 00000000 */
#define O_WRONLY 0x1 /* 00000001 */
#define O_RDWR 0x2   /* 00000002 */

#define O_CREAT 0x40       /* 00000100 */
#define O_EXCL 0x80        /* 00000200 */
#define O_NOCTTY 0x100     /* 00000400 */
#define O_TRUNC 0x200      /* 00001000 */
#define O_APPEND 0x400     /* 00002000 */
#define O_NONBLOCK 0x800   /* 00004000 */
#define O_DSYNC 0x1000     /* 00010000 */
#define O_ASYNC 0x2000     /* 00020000 */
#define O_DIRECT 0x4000    /* 00040000 */
#define O_LARGEFILE 0x8000 /* 00100000 */

#define O_DIRECTORY 0x10000 /* 00200000 */
#define O_NOFOLLOW 0x20000  /* 00400000 */
#define O_NOATIME 0x40000   /* 01000000 */
#define O_CLOEXEC 0x80000   /* 02000000 */

/*
 * __O_SYNC/__O_TMPFILE are Linux-kernel names in the implementation-reserved
 * namespace (this libc IS "the implementation", and the kernel UAPI mandates
 * the exact spellings) — the NOLINT below is the house waiver for that.
 */
#define __O_SYNC 0x100000 /* NOLINT(bugprone-reserved-identifier) 04000000 */
#define O_SYNC (__O_SYNC | O_DSYNC)
#define O_PATH 0x200000      /* 010000000 */
#define __O_TMPFILE 0x400000 /* NOLINT(bugprone-reserved-identifier) 020000000 */
#define O_TMPFILE (__O_TMPFILE | O_DIRECTORY)

/* ---- fcntl(2) commands ---- */

#define F_DUPFD 0
#define F_GETFD 1
#define F_SETFD 2
#define F_GETFL 3
#define F_SETFL 4
#define F_GETLK 5
#define F_SETLK 6
#define F_SETLKW 7
#define F_SETOWN 8
#define F_GETOWN 9
#define F_SETSIG 10
#define F_GETSIG 11

/* Linux-specific owner-identity commands (constants only; struct f_owner_ex
 * is out of POSIX scope and not provided). */
#define F_SETOWN_EX 15
#define F_GETOWN_EX 16
#define F_GETOWNER_UIDS 17

/* Open-file-description (OFD) locks, Linux 3.15+. */
#define F_OFD_GETLK 36
#define F_OFD_SETLK 37
#define F_OFD_SETLKW 38

#define F_DUPFD_CLOEXEC 1030 /* F_LINUX_SPECIFIC_BASE (1024) + 6 */

/* Close the descriptor on exec — the F_SETFD/F_GETFD flag. */
#define FD_CLOEXEC 1

/* Record-lock types (struct flock l_type). */
#define F_RDLCK 0
#define F_WRLCK 1
#define F_UNLCK 2

/* ---- *at(2) base-directory and behavior flags ---- */

#define AT_FDCWD (-100)
#define AT_SYMLINK_NOFOLLOW 0x100
#define AT_REMOVEDIR 0x200
#define AT_SYMLINK_FOLLOW 0x400
#define AT_EACCESS 0x200

/* ---- posix_fadvise(2) advice values ---- */

#define POSIX_FADV_NORMAL 0
#define POSIX_FADV_RANDOM 1
#define POSIX_FADV_SEQUENTIAL 2
#define POSIX_FADV_WILLNEED 3
#define POSIX_FADV_DONTNEED 4
#define POSIX_FADV_NOREUSE 5

/*
 * Record-lock descriptor, ABI-identical to the x86_64 kernel layout
 * (asm-generic/fcntl.h: short, short, long, long, int — 32 bytes with
 * natural padding). On x86_64 the LFS and non-LFS layouts are one struct,
 * so there is no separate flock64 here.
 */
struct flock
{
    short l_type;   /* F_RDLCK, F_WRLCK, or F_UNLCK */
    short l_whence; /* SEEK_SET, SEEK_CUR, or SEEK_END (from <unistd.h>) */
    off_t l_start;  /* relative offset of the locked region */
    off_t l_len;    /* region length; 0 means through EOF */
    pid_t l_pid;    /* PID of the process holding the lock (F_GETLK) */
};

/*
 * Perform one of the F_* control operations on fildes. Only the commands
 * that take a third argument read it from the varargs; all others pass 0,
 * which the kernel ignores. Return the command-specific result, or -1 with
 * errno set.
 */
int
fcntl(int fildes, int cmd, ...);

/*
 * Equivalent to open(path, O_WRONLY | O_CREAT | O_TRUNC, mode): create
 * path for writing, truncating any existing file, with mode masked by the
 * process umask. Return a file descriptor, or -1 with errno set.
 */
int
creat(const char *path, mode_t mode);

/*
 * Announce an expected access pattern for the range [offset, offset+len) of
 * fd (len 0 means through EOF). Unlike the rest of the family this returns
 * an error NUMBER directly — 0 on success, else the positive errno value
 * (e.g. EBADF, ESPIPE) — and errno is untouched (POSIX).
 */
int
posix_fadvise(int fd, off_t offset, off_t len, int advice);

/*
 * Ensure storage is allocated for the range [offset, offset+len) of fd,
 * growing the file as needed. Returns an error number directly (0 on
 * success) and leaves errno untouched, like posix_fadvise (POSIX).
 */
int
posix_fallocate(int fd, off_t offset, off_t len);

#if VLIBC_LEVEL_GE(2)

/* lockf() commands (POSIX XSI; the kernel has no lockf syscall — these are
 * userspace cmd values). */
#define F_ULOCK 0 /* unlock a previously locked region */
#define F_LOCK 1  /* lock a region, blocking until available */
#define F_TLOCK 2 /* try to lock; -1 with EACCES/EAGAIN if held */
#define F_TEST 3  /* test a region for another process's lock */

/*
 * Apply or remove an exclusive POSIX record lock on [current offset,
 * current offset + len) of fd (len 0 means through EOF). XSI. Return 0, or
 * -1 with errno set.
 */
int
lockf(int fd, int cmd, off_t len);

#endif /* VLIBC_LEVEL_GE(2) */

#ifdef __cplusplus
}
#endif

#endif /* VLIBC_FCNTL_H */